Osman began his journey by forming a friendship with Yorgopolos and the Kayi tribe expanded its influence further during the reign of Osman Ghazi, but some problems will hinder Osman and he must solve it.
The appearance of Adbali and his daughter, Bamsi bid farewell to his son Ibars, while sedition began to appear in the horizon between the Kayi tribe and the castle after the killing of Yorgopolos and Sofia accused Osman of killing him.
Seeing Helen and Sofia running down the aisle, Kalanoz went after her, suspecting her murder partner, Sofia, of getting involved in other things. Osman captured Teokles and the front of Theebali was blocked by Akca Dervis, Pehlivan and Zulfikar Dervis. After the trio, Bala Hatun took Osman to Edebali. I wonder what Edebali will tell Osman. What kind of plan will Dundar and Batur plan to plan for Dundar, whose daughter was kidnapped, and Zohre, who saw Osman as responsible for these events? What's the big surprise waiting for Kalanoz, who's going after Sofia and Helen.
Bala Hatun is kidnapped. Osman is imprisoned in a tent with his hands chained. Learning about Bala Hatun's abduction and outraged Osman's actions surprise everyone.
Yannis succeeded in realizing his bloody plan, raiding the market by the lake and kidnapping Edebali's daughter.
Osman took Bala Hatun's healing from Yannis and exposed Yannis.
Batur, Dündar's son, rescues Osman for a reputation in the tribe after one of Salvador's men is tricked. Edebali declines Osman's proposal leaving him devastated and upset.
Sofia tasks her lover, Kalanoz, to kill Şeyh Edebali but is killed in this attempt by Osman. Bamsı, Osman's loyal companion, converts Salvador to Islam. Salvador's new name is Sıddık.
Osman steals all the tax gold that was being transported illegally to Alişar Bey, the Selçuk Sançak Bey, by the Mongols. Yannis, disguised as a clairvoyant, proves to Alişar that Osman stole the gold. Alişar becomes an enemy of Osman.
Balgay, a Mongol commander, captures Söğüt and kills many women and children. He offers Osman that he will give him the Sançak Beylik and some more land if he was to become loyal to him. Osman rejects Balgay's offer.
Osman, with many difficulties, manages to escape the town with his alps. Balgay meets Yannis and Sofia and they decide to ally against Osman. Balgay even raids the Kayı tribe and has Osman's entire family in hostage until he comes. Konur, one of Osman's alps, also uncovers the fact that one of Balgay's men, Kongar, is his long-lost brother.
Osman, who has met the Aksakals, arrives in the tribe and gives Balgay Genghis Han's dagger in order to leave him and his tribe alone. Osman tasks Salvador to spy for him in Kulucahisar Castle, however, the cunning Sofia still doesn't trust him too much. Meanwhile, the tribe council, mainly Dündar, decides to expel Osman for rebelling against the Mongols. Osman later recaptures Söğüt with his alps.
Dündar is given the Sançak Beylik, angering Alişar, and Osman takes back the dagger he gave to Balgay secretly through an operation at his camp, humiliating him in front of the Mongol leaders. Bala is wounded by some Mongols and now cannot produce a baby.
After he kidnaps Sofia, Osman tells Yannis that he can have his daughter back if he asked Balgay to come to his castle, in the way he would ambush him. The ambush is successful but Batur is killed by Alişar, who has the intention of making Dündar and Osman fight.
Alişar pins the blame on Osman resulting in Dündar attacking Osman during the ambush. In Dündar's attack, Alişar, who is hidden behind the trees, aims at killing Osman with his arrow but accidentally hits Dündar instead. Balgay escapes but Gündüz, Osman's elder brother, successfully becomes the new substitute Bey of the Kayı tribe.
After his meeting with the Aksakals, Osman saves Princess Adelfa, a Byzantine princess being forced to marry Geyhatu. After saving her, he takes her to his tribe and asks Bala and Selcan to take special care of her.
Zöhre, Dündar's devious wife who even had Gündüz kidnapped by Balgay earlier, plans to take Adelfa to Alişar in spite of Bala and Selcan through her adoptive daughter, Burçin.
Kongar reverts to Islam and becomes Göktug after a contract is shown to him that he was actually bought by Balgay from a slave-trader. Meanwhile, Osman is tasked by the Aksakals to save his uncle, Sungurtekin, who was spying for them in the Margarit Monks and his betrayal is now caught, Osman succeeds and embraces his thought-dead uncle.
Osman ambushes Dündar and Zöhre, who were taking their daughter, Aygül, to get her married to Alişar, he sought to show them that he didn't kill Batur. He trusts Aygül that she believed him that he didn't kill Batur, however, as she didn't trust him from the start, when she is let go, she tells Alişar everything and asks him to save her parents. Later, Aygül's parents are freed because of her betrayal.
Balgay captures Osman while Böke, the Mongol commander who informed the monks about Sungurtekin's betrayal, supposedly allies with Balgay to save his life, however, with the help of Göktug, disguised as Kongar, Osman escapes but is severely wounded by arrows.
Göktug continues to spy for Osman at Balgay's camp while Osman recovers with the help of Şeyh Edebali and sees a dream which results in Edebali allowing Osman to marry Bala.
Osman tasks Gündüz and Bala to invade Alişar's mansion where they are successful. Meanwhile, Osman captures Alişar when he is away and forces him to reveal to Dündar that he killed Batur. After seeing this, Dündar begs for forgiveness. Böke also dies in an ambush and Osman takes Alişar to the tribe and is ready to behead him only to be stopped by Geyhatu's commander, Subutay.
Osman ignores Subutay's threats and beheads Alişar. Sofia escapes the Emperor who sentenced Yannis and most of the Margarit Monks to death. Hazal[v], Dündar's first wife, arrives and kills Zöhre for poisoning Osman and Bala's wedding food, which was given to her indirectly through Sofia. Meanwhile, Balgay finds out that Göktug has been betraying him and gives him a potion that messes up his memory and changes him into Kongar again.
Aygül is currently mentally ill after she learnt the truth about Alişar. Sıddık's betrayal is caught by Sofia and thus he is martyred while Subutay allies with Balgay and Sofia to destroy the Kayı tribe in an attack. Osman, who is aware of the attack, prepares for it and therefore, Subutay's plans backfire.
Subutay is beheaded, however, Sofia escapes with the help of Balgay. Kongar becomes a Muslim again after remembering everything but bids farewell to Konur, who was accidentally killed by him when he was drunk with the potion. In an epic showdown, Balgay is supposedly killed by Osman along with the supposed death of Cerkutay by Göktug in the presence of Sofia and her 'dark knights', a special sort of knights, who keep on fighting till they die. However, Cerkutay manages to survive the attack.
The 'dark knights' injure Osman very badly and everyone believes he is dead, however, Osman is actually alive but he only tells Gündüz, Bala and Selcan. Taking advantage, Osman conquers Kulucahisar Castle and kills Sofia in the process. Aygül, who is mentally ill, attempts to kill Hazal because she killed her mother, however, the arrow accidentally kills Burçin instead.
